Schiaparelli is being installed at the top of the Trace Gas Orbiter, at Thales Alenia Space, in Cannes, France, for final integrated tests in 2015. Click to enlarge. Credit: ESA

Pre-launch processing of the Schiaparelli lander in Baikonur on January 19, 2016. Click to enlarge. Credit: ESA

Artist depiction of the separation between the TGO orbiter and the Schiaparelli lander in October 2016. Click to enlarge. Credit: ESA

The full-scale qualification model of the parachute for the Schiaparelli lander undergoes the pyrotechnic mortar deployment tests in the world’s largest wind tunnel, operated by the United States Air Force at the National Full-Scale Aerodynamic Complex, NFAC, in the Ames Research Center, California. Tests of how the parachute will inflate at supersonic speeds were carried out with a smaller model in a supersonic wind tunnel in the NASA Glenn Research Center. Click to enlarge. Credit: ESA

COMARS+ instruments. Click to enlarge. Credit: ESA/DLR

Descent Camera, DeCa, for the Schiaparelli lander. Credit: ESA.

Locations of COMARS+ sensors. Click to enlarge. Credit: ESA/DLR

An artist rendering of the Schiaparelli lander on the surface of Mars. Click to enlarge. Credit: ESA

Schiaparelli to make Europe's second Mars landing attempt

The Schiaparelli lander (previously known as Entry Descent and Landing Demonstrator Module, EDM) will be only the second European attempt to land on Mars after the ill-fated mission of the Beagle-2 lander which disappeared on the surface of the Red Planet after a seemingly normal separation from the Mars Express orbiter on Dec. 25, 2003. For the new attempt within the ExoMars-2016 project, the European Space Agency, ESA, funded the development of the 600-kilogram disc-shaped test vehicle with a primary goal of learning to land on Mars.

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EDM concept

According to ESA, the ExoMars-2016 descent module builds on a heritage of designs that have been evaluated and tested by the agency during earlier ExoMars studies. They include a special material for thermal protection, a parachute system, a radar Doppler altimeter system and liquid-propellant braking engines. The module accommodates a series of sensors that will monitor the behavior of all key technologies of landing. The data will be sent back to Earth for post-flight reconstruction in support of future European missions to Mars, ESA said.

On November 8, 2013, the agency announced that the EDM lander would be named Schiaparelli, after the 19th-century astronomer Giovanni Virginio Schiaparelli, who produced some of the best contemporary maps of Mars, even though his name primarily associated in popular literature with his "discovery" of "canals" on the planet in 1877.

Although the official primary goal of the Schiaparelli lander is to acquire know-how for landing on Mars, it is not entirely clear how exactly this experience could be applied. The follow-on ExoMars-2018 lander currently built in Russia for the joint European-Russian project is considered to be too large, too different and too far in development to expect any major lessons from Schiaparelli, industry sources said. In addition, the atmospheric entry technologies and related avionics have direct military applications, for example in warheads of ballistic missiles, and their transfer between Europe and Russia might present some political pitfalls, sources said.

The heat shield is a carbon sandwich structure covered with 90 tiles known as Norcoat Liege, a thermal ablative material made of resin and cork.

The rear cover, which contains the parachute and several engineering sensors (in particular, COMARS+) to measure aerothermal parameters, is composed of 93 tiles (in 12 different shapes), attached to a carbon sandwich structure. A mass of the bonding agent, which glues tiles to a heat shield had to be controlled with a precision exceeding one gramm and each tile had to be positioned with an accuracy of less than one millimeter.

A 12-meter supersonic parachute made out of nylon fabric and held by Kevlar lines will be deployed with a help of mortar to reduce speed below supersonic. The so-called disk-gap-band canopy design of the parachute is largely inherited from a similar system, which helped to land the European-built Huygens lander on the surface of Saturn's Moon Titan.

There are three 17.5-liter propellant tanks on Schiaparelli with about 15 kilograms of hydrazine each. Propellant tanks are pressure fed with the help of 15.6 liters of helium stored in a tank under pressure of 170 bar. The tanks feed three sets of three engines for the final phase of the landing.

COMARS+ instruments

According to ESA, the Combined Aerothermal and Radiometer Sensors Instrument Package, COMARS+, will measure aerothermal parameters on the exterior of Schiaparelli as it passes through the Martian atmosphere.

COMARS+ consists of three combined sensors spaced equally across the back cover of Schiaparelli, one broadband radiometer, and an electronic box hidden inside the module. The entire package weighs 1.73 kilograms and draws 4.5 watts of power.

The sensors, located on the back cover of the module, will measure the pressure, the temperature of the module's surface, the rate at which heat energy is transferred to the surface (total heat flux rate), and the amount of radiated heat from the hot gas to the back cover (radiative heat flux).

Two so-called ICOTOM narrow band radiometers in each COMARS sensor are provided by the French space agency, CNES. In addition, a broad-band radiometer provided by the German aerospace agency, DLR, is integrated close to the COMARS 3 sensor. The data produced from this instrument package will provide essential input for the improved design of future missions landing on Mars.

The COMARS+ package is provided by the DLR.

In addition, the AMELIA payload will be used for entry and descent science data collection using onboard engineering sensors.

Schiaparelli Descent Camera, DeCa

Finally, a 0.6-kilogram, engineering camera was installed on the lander to capture 15 black and white images of the approaching surface during the descent. The device is a refurbished spare flight model of the Visual Monitoring Camera flown on ESA’s Herschel/Planck spacecraft to image the separation of the two craft after their joint launch. Developed at Optique et Instruments de Precision, OIP, of Belgium, the DeCa system fits into a nine-centimeter box.

During the Schiparelli's landing, photos should help reconstruct the module’s trajectory and its motion, as well giving context information for the final touchdown site. The camera has a wide, 60-degree view angle to maximise the chances of seeing features that will help to pinpoint the landing site and reveal Schiaparelli’s attitude and position during descent.

There will be no live transmission of images, instead they will be stored in its memory for the uplink via NASA's Mars Reconnaisance Orbiter, MRO, a day after landing.

Communications

From its coasting to Mars and until its landing, Schiaparelli will communicate with its TGO "mother ship", sending the most critical data in real time via a pair of UHF antennas: one on the backshell of the heatshield for use during entry, and the spiral-shaped antenna on the top deck of the lander after it separates from the parachute.

Surface operations

If the landing is succesful, the pre-programmed sequence will operate the Schiaparelli's science instruments for at least two days – and possibly longer. The science activities are designed to make the most of the limited energy available from the batteries, so they will be performed in set windows rather than continuously – typically, for six hours each day.

The timeline will also switch on the module’s transmitter during a series of fixed slots to send recorded data up to ESA and NASA orbiters passing overhead, which will then transmit the data to Earth. These relay slots include 32 by NASA craft: 18 by the Mars Reconnaissance Orbiter, eight by Odyssey and six by Maven. ESA’s Mars Express will make 14 overflights.

During the critical arrival activities, several of NASA’s 34-meter deep-space stations will provide a ‘hot back-up’ to ESA’s stations, ensuring that there is no loss of communication at a time when any delay in commanding could have serious effect on orbit entry or landing.

Surface instruments

The Schiaparelli lander carries a small science payload, called DREAMS, which stands for Dust Characterization, Risk Assessment and Environment Analyzer on the Martian Surface. The package is designed to study Martian environment and consists of several sensors:

MetWind to measure the local wind speed and direction;

DREAMS-H to monitor humidity;

DREAMS-P to register pressure;

MarsTem to measure atmospheric temperature near the surface;

The Solar Irradiance Sensor, SIS, to measure the transparency of the atmosphere;

The payload is expected to operate on the surface of Mars from two to eight sols.

In addition, a tiny set of laser retro-reflectors was attached almost at the last minute in the development of Schiaparelli to its the zenith-facing surface. The reflectors do not require any power and could be used in the future as a target for Mars orbiters to laser-locate the module.